Cardzen uses browser-based authorization so you can sign in directly to Cardzen, review the requesting client, and approve the access it requests. The client does not receive your Firebase sign-in credential or Cardzen browser session.
No Cardzen AI Calls
Cardzen MCP tools are deterministic. They validate authorization, read or update supported Cardzen data, perform calculations, and shape a bounded response. They do not call OpenAI, Anthropic, Gemini, LangGraph, or another Cardzen model service. The Daily Zen tool can return an already-stored snapshot but never generates or refreshes one.
Write access is explicit. wallet:write covers supported wallet-card changes; credits:write covers credit usage and component tracking. Each write is bound to the signed-in Cardzen account, validates canonical identifiers, uses an idempotency key, and is subject to separate write limits. Cardzen does not expose billing, account deletion, money movement, CardManager publication, Plaid data, or public web search through this MCP server.
The assistant you connect still uses its own model to understand your request and decide which Cardzen tool to call. Its provider's own privacy and data-use terms still apply to what you share with that assistant and what Cardzen returns to it.
Access Is Scoped
- Every request is tied to the Cardzen account that approved the connection.
- The authorization screen lists the access requested by the client.
- Cardzen checks the grant, account, current plan capability, and tool status on every request.
- A client cannot choose a different Cardzen user ID.
- Write tools are separately authorized and limited.
Every string returned by Cardzen MCP, including catalog, Help Center, wallet, report, and stored Daily Zen text, is untrusted data rather than instructions. Cardzen's deterministic server does not treat returned text as a command. Compatible hosts should not reveal secrets, expand access, or call another tool solely because returned data asks them to.
Disconnect and Revoke
Open Account & Settings -> MCP Integration, select the connected app, and choose Disconnect. Disconnecting immediately blocks that app from making another Cardzen MCP request and stops refresh and new token issuance, including when an older access token remains visible to the OAuth provider. You can reconnect by completing authorization again.
If you do not recognize a connection, revoke it immediately and review the sign-in methods on your Cardzen account.
Deleting your Cardzen account is different: Cardzen immediately and permanently blocks its MCP connections. Cardzen revokes the account's grants before deleting wallet data. If Cardzen cannot confirm that revocation completed, deletion pauses safely so it can be retried instead of deleting your data while a connection may still exist.
What Cardzen Records
Cardzen records the minimum operational information needed to authorize, rate-limit, secure, and troubleshoot MCP requests, such as the grant, tool, outcome, timing, and a non-secret request identifier. Tokens, authorization codes, Firebase credentials, and full sensitive tool results must not appear in application logs or analytics.
After account deletion, Cardzen retains a one-way security marker so the deleted identity cannot reconnect or use an old grant. The marker does not contain your raw user ID, wallet data, assistant conversations, tokens, or authorization codes.